Showing papers by "University of Auckland published in 1986"

A review of estimating animal abundance.

Abstract: During the past 5 years there have been a number of important developments in the estimation of animal abundance and related parameters such as survival rates. Many of the new techniques need to be more widely publicized as they supplant previous methods. The aim of this paper is to review this literature and suggest further avenues for research.

Clinical Pharmacokinetics and Pharmacodynamics of Warfarin. Understanding the Dose-Effect Relationship

Abstract: The simplest complete system accounting for the time-course of changes in the prothrombin time induced by warfarin requires the combination of 4 independent models: 1. A pharmacokinetic model for the absorption, distribution, and elimination of warfarin. Warfarin is essentially completely absorbed, reaching a maximum plasma concentration between 2 and 6 hours. It distributes into a small volume of distribution (10 L/70kg) and is eliminated by hepatic metabolism with a very small clearance (0.2 L/h/70kg). The elimination half-life is about 35 hours. 2. A pharmacodynamic model for the effect of warfarin on the synthesis of clotting factors (prothrombin complex). Prothrombin complex synthesis is inhibited 50% at a warfarin concentration of about 1.5 mg/L. Warfarin concentrations associated with therapeutic anticoagulation are of similar magnitude. 3. A physiological model for the synthesis and degradation of the prothrombin complex. The synthesis rate is about 5%/h/70kg and the elimination half-life estimated from changes in prothrombin time is approximately 17 hours. On average it will take 3 days for the anticoagulant effect of warfarin to reach a stable value when warfarin concentrations are constant. 4. A model for the relationship between the activity of prothrombin complex and the prothrombin time. In general there is a hyperbolic relationship between these quantities. Its exact shape depends upon the method used for measuring the prothrombin time.

Impaired wound healing in surgical patients with varying degrees of malnutrition.

Abstract: The relationship between nutritional state and wound healing was examined in 66 adult surgical patients. Wound-healing response was assessed by measuring the collagen content (hydroxyproline) of fine tubes of Gore-tex inserted subcutaneously along standardized needle track arm wounds. After a period of 7 days, the tubes were removed and it was found that there was a higher hydroxyproline content in the tubing of 36 normally nourished patients than there was in the tubing of 21 patients with mild protein energy malnutrition (p less than 0.01) and 9 patients with moderate to severe protein energy malnutrition (p less than 0.01). There was no difference in the wound-healing response between the two latter groups of patients who had significantly different degrees of malnutrition. The results suggest that a definite abnormality in the wound-healing response exists in malnourished surgical patients, but it occurs earlier in the course of the illness than previously supposed.

Crosscorrelation between the envelopes of 900 MHz signals received at a mobile radio base station site

Abstract: An experimental investigation is reported of the crosscorrelation of 900 MHz signals received by two spatially separated antennas at a base station. The investigation embraced vertical, horizontal and combined horizontal and vertical separation of the antennas, for transmission from test routes 1.3 km from the base station. It was found that a crosscorrelation ≤0.7 (i.e. when diversity improvement becomes significant) can best be achieved using vertical separation of the antennas of between 11 λ and 13 λ for the 1.3 km cell radius. At 900 MHz such an antenna separation is easily obtained and, in addition, the roof space required is small. Moreover, the crosscorrelation using vertically spaced antennas is independent of the incoming arrival angle (unlike horizontally spaced antennas), and hence low correlation can be achieved while maintaining omnidirectional coverage.

Fitting Logistic Models Under Case‐Control or Choice Based Sampling

Abstract: On compare deux approches dans le cas important de l'ajustement des modeles de regression logistique

Low Serum Osteocalcin Levels in Glucocorticoid-Treated Asthmatics

Abstract: . Serum osteocalcin (OC) levels were measured in 19 asthmatic patients receiving long term glucocorticoid therapy and in age- and sex-matched asthmatic patients not receiving this treatment. In the glucocorticoid-treated patients, the meanOC level was approximately 50% less than that in the control group (P < 0.001), and there was a direct correlation between serum OC and 1,25-dihydroxyvitamin D [1,25-(OH)2D; r = 0.71; P < 0.001]. Multiple regression analysis in a total of 39 glucocorticoid- treated patients indicated that OC correlated directlyto 1,25-(OH)2D and inversely to glucocorticoid dose. There was no correlation between OC and 1,25-(OH)2D in the control group and no significant difference in mean serum 1,25-(OH)2D between the steroid-treated asthmatic patients and the asthmatic control patients. The effect of a 4-day course of oral 1,25-(OH)2D on serumOC was studied in six patients with glucocorticoid excess and six normal subjects. There was a similar percent increase in OC levels in bot...

Influence of surface slicks on the distribution and onshore movements of small fish

Abstract: The surface slicks of internal waves were sampled in continental shelf waters off the east coast of Northland, New Zealand, from 1982–1985. Densities of small fish and zooplankton from surface waters were higher in slicks than in the rippled water adjacent to them. Presettlement fish, of species found as adults nearshore, were abundant in ichthyoplankton samples and visual counts from slicks. These fish ranged from fish with primordial fins to those with adult fin-ray counts. Some small reef fish aggregated around drift algae. Drift algae were also abundant in slicks. Slicks moved at 0.5 to 1.25 km h-1 in the direction of shore. Hence, a consequence of aggregation in slicks is that presettlement fish may be transported onshore. When slicks were absent, drift algae were found in scattered patches at different distances from shore. In the presence of slicks algae were aligned in them. Internal waves, therefore, may have the ability to turn scattered distributions into regular patterns. Because the surface slicks that internal waves produce are common coastal features, we should modify our perspective of how small fish and zooplankton are distributed in local water masses. Furthermore, the occurrence of internal waves should influence the way in which surface waters are sampled. We suggest that fish settlement patterns need to be investigated concurrently with measurements of physical mechanisms which may promote aggregation, and onshore movements of small fish (e.g. internal waves). These waves may contribute to the variability in settlement rates of small fish.

Accuracy of certification of deaths due to asthma a national study

Abstract: In a two-year study of asthma mortality in New Zealand conducted between August 1981 and July 1983, the certified cause of death and its subsequent statistical coding was compared with the opinion of a panel of respiratory physicians who had made detailed enquiry into the medical history and circumstances surrounding the death of each patient. When the panel's opinion was taken as the reference standard, the national health statistics overestimated asthma mortality for all age groups by 26.0%. For patients aged 15-64 years, the net overestimate was 12.9%, no greater than that found in a similar study in this age group in the United Kingdom. Failure of certifying doctors and coroners to follow appropriate procedures for identification of the primary condition leading to death, or misdiagnosis of other lung disease as asthma, accounted for most inaccuracies in certification. In patients under age 35 years, certification and statistical coding of asthma death was considered accurate in 97.8% of all cases, but accuracy declined with increasing age. The high New Zealand asthma mortality rate, especially in young people, could not be explained by inaccuracies in death certification or statistical coding.

Oxytocin, Oxytocin-Associated Neurophysin, and Prostaglandin F2α Concentrations in the Utero-Ovarian Vein of Pregnant and Nonpregnant Sheep

Abstract: Oxytocin, oxytocin-associated neurophysin (neurophysin), prostaglandin F2α (PGF2α), and progesterone concentrations were measured in the utero-ovarian vein (UOV) of sheep during the estrous cycle and early pregnancy. On days 13- 16 of the cycle, large pulses of PGF2α, oxytocin, and neurophysin were measured in samples collected at hourly intervals from the UOV draining a corpus luteum (UOV/CL). Most of the PGF2α pulses (96.5%) coincided with a pulse of both oxytocin and neurophysin, whereas only 55.6% of oxytocin pulses coincided with a pulse of PGF2α. Therefore, during luteolysis in sheep, uterine PGF2α release is closely associated with ovarian oxytocin release, and oxytocin release is unlikely to be dependent upon a uterine PGF2α stimulus. During frequent sampling, coincident oxytocin pulses were measured in 1) both UOVs when a CL was present in both ovaries and 2) the jugular vein, carotid artery, and UOV/CL, with a significantly higher oxytocin pulse concentration occurring in jugular venous compared...

Carbene and Carbyne Complexes of Ruthenium, Osmium, and Iridium

Abstract: Publisher Summary This chapter discusses the carbene and carbyne complexes of ruthenium, osmium, and iridium. The importance of transition-metal carbene complexes and of transition-metal carbyne complexes is now well appreciated. The wealth of empirical information collected for transition-metal carbene and carbyne complexes may be best interpreted within the framework of sound theoretical models for these compounds. Theoretical studies of metal–carbene complexes have been undertaken by several groups. The chemistry of transition metal–carbyne complexes is rather less developed than the chemistry of carbene complexes. The development of the chemistry of carbene complexes of the Group 8A metals, Ru, Os, and Ir, parallels chemistry realized initially with transition metals from Groups 6 and 7. Although transition-metal alkylidene complexes––that is, carbene complexes––containing only hydrogen or carbon-based substituents were first recognized over 15 years ago, it is only relatively recently that Ru, Os, and Ir alkylidene complexes have been characterized. In 1980, a stable dichlorocarbene complex of osmium (II) was described, and since then a large number of dihalocarbene complexes of ruthenium, osmium, and iridium has been prepared. Transition-metal carbyne complexes are still relatively uncommon as only a few synthetic approaches to these compounds have proved generally applicable. M=C and M=C bonds are now well-established features of the chemistry of Ru, Os, and Ir. Many exciting possibilities exist for using these functions in further reactions.

A Kalman filtering approach to short-time Fourier analysis

Abstract: The problem of estimating time-varying harmonic components of a signal measured in noise is considered. The approach used is via state estimation. Two methods are proposed, one involving pole-placement of a state observer, the other using quadratic optimization techniques. The result is the development of a new class of filters, akin to recursive frequency-sampling filters, for inclusion in a parallel bank to produce sliding harmonic estimates. Kalman filtering theory is applied to effect the good performance in noise, and the class of filters is parameterized by the design tradeoff between noise rejection and convergence rate. These filters can be seen as generalizing the DFT.

Effects of sustained swimming on rainbow trout muscle structure, blood oxygen transport, and lactate dehydrogenase isozymes: evidence for increased aerobic capacity of white muscle.

Abstract: Groups of rainbow trout (Salmo gairdneri, Richardson) were continuously swum at 20 cm s-1 (1.0 body lengths s-1) for 0, 3, 30, and 200 days. No significant changes in fish condition factor, combined red and white muscle mass, muscle fibre size or fibre size distribution were observed. After 200 days of swimming there was a significant 2.2 fold increase in red muscle mass. Number of capillaries per red muscle fibre increased significantly in each group by a maximum of 27% after 200 days exercise. Number of capillaries per white muscle fibre increased significantly by 95% after 200 days exercise. Blood lactate, haemoglobin (Hb) concentration haematocrit, erythrocyte adenosine triphosphate, and whole blood oxygen affinity P50 were unchanged by swimming. After 30 and 200 days swimming there was a shift in expression of white muscle lactate dehydrogenase (LDH) isozymes from LDH-A to LDH-B. Within the duplicated LDH-B isozyme complex, there was a shift in expression from LDH-B to LDH-B' subunits. These results suggest that sustained swimming at 1(-1) bl s-1 increased the aerobic capacity of red and particularly white (fast) muscle of rainbow trout but did not alter the gas transport characteristics of the blood.

Anatomical changes during adventitious root formation.

Abstract: Organization is one of the most characteristic traits of living organisms. It is especially conspicuous in the orderly growth that every organism undergoes and which produces the specific forms so characteristic of a particular species [1]. The evidence for biological organization is manifested in studies in which the normal processes of growth and development are modified experimentally, e.g. by removing parts of the growing body. Thus, a ‘cutting’ removed from a plant, under appropriate conditions, may produce a new root system and finally an entire individual with a balanced ratio of root to shoot. These regeneration processes are present in a great range of plants. Roots that originate in locations other than from the embryo or as branches of the primary root are termed adventitious [2, 3]. They may arise spontaneously on intact plants, especially at nodes of prostrate stems and on rhizomes, or stolons or they may develop only as a response to damage when part of the plant has been deliberately or accidentally severed from the existing root system. This involves various anatomical changes associated with wound responses in addition to those involved in root formation itself. Adventitious roots are produced vigorously and rapidly in some species under appropriate conditions, but much less readily in others, and plants can be grouped according to their ease of rooting (Fig. 1).

Seismic design of storage tanks

Abstract: A study group of the New Zealand National Society for Earthquake Engineering has recently completed recommendations for the Seismic Design of Storage Tanks, in a form suitable to be used as a code by the design profession. The recommendations cover design criteria, loading, actions and details and are based on a consistent philosophy of serviceability under the design level earthquake. This paper provides a review of the study group's recommendations.

Crystal Growth and the Role of the Organic Network in Eggshell Biomineralization

Abstract: A model based on geometrical crystal growth considerations is proposed for the deposition of the crocodilian, testudinian and avian eggshells. In each shell column, crystal deposition is initiated at a single location, from which growth fans out at all angles to the shell normal. In both calcitic and aragonitic shells, growth is in the [001] direction, resulting in an increase in the degree of (001) preferred orientation with distance from nucleation. Where there is unhindered crystal growth, the shells show a crystalline fracture morphology, and the degree of texture that develops is a simple function of the column radius. This type of growth makes up the whole of the testudinian shell, the inner 0.3-0.4 (30-40%) of the thick ratite shells and the cone layer of the other avian shells. At the start of the palisade layer of the avian shell, the onset of deposition of the organic component coincides with a hindrance to texture development, which thereafter proceeds at a lower rate. A further hindrance occurs about halfway through the shell, probably caused by a change in the physical characteristics of the organic network. The degree of texture that develops in the avian shell is a function of the column radius and the degree of physical hindrance presented by the organic network. The palisade layer of the avian shell has a composite fracture morphology resulting from the intermingling of the network with the inorganic phase. The organic component does not appear to control crystal growth, as previously believed, but instead acts as a reinforcing fibrous network.

The effects of hydrocortisone, parathyroid hormone and the bisphosphonate, APD, on bone resorption in neonatal mouse calvaria.

Abstract: The effects of hydrocortisone and parathyroid hormone (PTH) upon bone resorption rates in neonatal mouse calvaria have been studied. Bone resorption (measured as 45Ca release) was significantly increased by hydrocortisone (10(-7) M and 10(-6) M) and there was a dose-dependent rise with PTH (0.3-0.9 micrograms/liter). When both PTH 0.3 micrograms/liter and hydrocortisone 10(-8) M were present in the incubating medium, bone resorption did not differ from control, but increasing the hydrocortisone concentration to 10(-7) M augmented 45Ca release by 25% (P less than 0.02) and doubling of the PTH level was associated with a 10% increase (nonsignificant). When both PTH and hydrocortisone were present in the higher concentrations (0.6 micrograms/liter and 10(-7) M, respectively) 45Ca release increased by 39% (P less than 0.005) above that resulting from the lower levels of both hormones (0.3 micrograms/l and 10(-8) M, respectively). (3-Amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) in concentrations of 3 X 10(-5) M and 10(-4) M, produced inhibition of basal and hydrocortisone/PTH-stimulated bone resorption without evidence of toxicity. These results indicate that hydrocortisone stimulates bone resorption in neonatal mouse calvaria in vitro, in contrast to the results found in fetal rat bone culture systems. PTH has a similar effect, which is additive to that of hydrocortisone and the combined stimulation can be overcome by APD. The possible relevance of these results to the development and prevention of glucocorticoid-induced osteoporosis is discussed.

Ultrastructural evidence for fibril-to-fibril associations in articular cartilage and their functional implication.

Abstract: This study presents ultrastructural evidence for the presence of a variety of fibril-to-fibril interactions or associations in the architecture of the general matrix of articular cartilage. These interactions are believed to serve a higher purpose of repeatedly constraining an overall radial arrangement of fibrils into an array of oblique interconnecting segments thus creating a three dimensional meshwork within which the hydrated ground substance is constrained. It is argued that any reduction in these interfibrillar interactions will allow the oblique fibril segments to revert to a low energy radial configuration, thus explaining the presence of such arrays prominent in various degenerate forms of articular cartilage.

Epidemiology of varicose veins.

Abstract: The prevalence rate of varicose veins in adults varies from less than 1% in lowland New Guinea women to over 50% in women in south Wales. Within populations the prevalence increases with age, is generally greater in women, is directly related to body mass, has an inconsistent relationship with occupation, and usually increases with increasing parity. None of these factors explain the striking geographic variation in the occurrence of varicose veins. The 2 most plausible hypotheses implicate low-fiber diets and prolonged chair-sitting as the primary causal factor. Epidemiological studies are required within populations to establish the merits of these 2 competing hypotheses. Since varicose veins are potentially preventable, further research is well justified.